كتاب الجنة وصفة نعيمها وأهلها
53  
The Book of Paradise, its Description, its Bounties and its Inhabitants
(17)
Chapter: The Deceased Is Shown His Place In Paradise Or The Fire; And Confirmation Of The Torment In The Grave - We Seek Refuge With Allah From That
(17)
بَاب عَرْضِ مَقْعَدِ الْمَيِّتِ مِنْ الْجَنَّةِ أَوْ النَّارِ عَلَيْهِ وَإِثْبَاتِ عَذَابِ الْقَبْرِ وَالتَّعَوُّذِ مِنْهُ
Sahih Muslim 2871 b

Al-Bara' b. 'Azib reported that this verse:

"Allah keeps those who believe steadfast with firm word in this world and the Hereafter" was revealed in connection with the torment of the grave.
حَدَّثَنَا أَبُو بَكْرِ بْنُ أَبِي شَيْبَةَ، وَمُحَمَّدُ بْنُ الْمُثَنَّى، وَأَبُو بَكْرِ بْنُ نَافِعٍ قَالُوا حَدَّثَنَا عَبْدُ الرَّحْمَنِ، - يَعْنُونَ ابْنَ مَهْدِيٍّ - عَنْ سُفْيَانَ، عَنْ أَبِيهِ، عَنْ خَيْثَمَةَ، عَنِ الْبَرَاءِ بْنِ عَازِبٍ، ‏{‏ يُثَبِّتُ اللَّهُ الَّذِينَ آمَنُوا بِالْقَوْلِ الثَّابِتِ فِي الْحَيَاةِ الدُّنْيَا وَفِي الآخِرَةِ‏}‏ قَالَ نَزَلَتْ فِي عَذَابِ الْقَبْرِ ‏.‏
Reference : Sahih Muslim 2871b
In-book reference : Book 53, Hadith 89
USC-MSA web (English) reference : Book 40, Hadith 6866
  (deprecated numbering scheme)